So if your chief told you that you must assist to work... You just go for 2 seconds?
Or if somebody told you that you must be poor to enter to a club, you become poor for 2 seconds and they will let you be in the club, even knowing that you are not poor anymore?

What I SHOULD do and what I CAN do are 2 very different things. You're thinking logically but not technically. If the club rules entitled that you had to be poor to join than even if I get rich I should still be allowed to stay in the club. Likewise, if my boss said I had to help out or I would be fired as long as I helped out even for 2 seconds I technically did what he told me to.